The present invention generally relates to the construction of fluid storage vessels for containing liquids or gases and, in a preferred embodiment thereof, more particularly relates to a specially designed water heater incorporating therein an all polymeric, integrally molded water heater storage tank and outer jacket construction.
Using conventional construction techniques a water heater is typically fabricated by providing a metal storage tank adapted to hold a quantity of water to be heated and later discharged from the tank for use by a remote fixture such as a sink. The tank is externally insulated by wrapping the tank with an appropriate insulation material, such as fiberglass blanket insulation, and then placing a metal jacket structure outwardly around the insulation material to hold it in place and shield it from damage. Alternatively, the blanket insulation may be omitted and foam insulation injected into the space between the tank and jacket structure.
This typical three-component water heater construction (i.e., separate metal tank, exterior metal jacket, and interior insulation medium) has associated therewith several well known problems, limitations and disadvantages. For example, the interior metal storage tank is heavy and, after a period of use, is subject to corrosion to an extent requiring that the entire water heater be replaced. Additionally, the fabrication of the overall water heater assembly is quite labor intensive, requiring various assembly steps and techniques including forming the tank, wrapping it with insulation (or injecting foam type insulation into place), and fabricating and installing the outer metal jacket structure.
This, of course, adds considerably to the cost of the finished water heater. Moreover, the insulation and outer jacket structure function primarily to thermally insulate the tank, and do not appreciably reinforce the tank against the pressure of the stored water therein. Accordingly, the separate metal tank must be designed to solely bear the stored water pressure force, thereby increasing the required thickness (and thus the weight) of the tank. These problems, limitations and disadvantages associated with the internal storage vessel portion of a water heater are not limited to water storage vessels, but occur as well in other types of fluid storage structures for both liquids and gases.
As can be readily seen from the foregoing, it would be highly desirable to provide, representatively for a water heater, an improved fluid storage vessel and associated fabrication methods, which eliminates or at least substantially reduces the above-mentioned problems, limitations and disadvantages. It is accordingly an object of the present invention to provide such an improved fluid storage vessel and associated fabrication methods.